#include <stdio.h>

int myStrcmp(const char* s1, const char* s2)
{
    int def = 0;
    while (1)
    {
        def = (int)((*s1) - (*s2));
        if (def != 0)
            return def;

        if (*s1 != '\0' && *s2 != '\0')
        {
            s1++;
            s2++;
        }
            break;
    }
    return def;
}

int main(void)
{
    const char* s1 = "abcd";
    const char* s2 = "abcd";

    printf("%d\n", myStrcmp(s1, s2));

    return 0;
}